Official investigators have compiled a substantial amount of evidence relating to suspected chemical attacks in Syria. This page provides links to the various reports compiled by four different bodies: the initial UN mission headed by Åke Sellström; the OPCW's Fact-Finding Mission (FFM); the UN-OPCW Joint Investigative Mechanism (JIM) and the OPCW's Investigation and Identification Team (IIT).
Incidents are listed chronologically with links to the relevant reports.
2013
Ghouta, Damascus
21 August 2013
UN mission report S/2013/553 (13 September 2013):
"Clear and convincing evidence that surface-to-surface rockets containing the nerve agent Sarin were used."
2014
Al Tamanah, Idlib province
12 April to 25 May 2014
FFM report S/1212/2014 (10 September 2014):
"Compelling confirmation" that a toxic chemical was used as a weapon, systematically and repeatedly. "High degree of confidence" that chlorine, either pure or in mixture, was the toxic chemical in question.
FFM report S/1230/2014 (18 December 2014):
Further details of incidents.
Talmenes, Idlib province
21 and 24 April 2014
FFM report S/1212/2014 (10 September 2014):
"Compelling confirmation" that a toxic chemical was used as a weapon, systematically and repeatedly. "High degree of confidence" that chlorine, either pure or in mixture, was the toxic chemical in question.
FFM report S/1230/2014 (18 December 2014):
Further details of incidents.
JIM 3rd report (24 August 2016):
"Sufficient information" to conclude that an incident on 21 April 2014 was caused by a Syrian armed forces helicopter dropping a device, followed by the release of a toxic substance that affected the population.
Kafr Zita, Hama province
2014 (various dates)
FFM report S/1212/2014 (10 September 2014):
"Compelling confirmation" that a toxic chemical was used as a weapon, systematically and repeatedly. "High degree of confidence" that chlorine, either pure or in mixture, was the toxic chemical in question.
FFM report S/1230/2014 (18 December 2014):
Further details of incidents.
2015
Idlib province (including Sarmin and Qmenas)
16 March 2015 to 20 May 2015
FFM report S/1319/2015 (29 October 2015):
Several incidents "likely" to have involved use of a toxic chemical as a weapon. "There is insufficient evidence to come to any firm conclusions as to the identification of the chemical, although there are factors indicating that the chemical probably contained the element chlorine."
JIM 3rd report (24 August 2016):
"Sufficient information" to conclude that a Syrian armed forces helicopter dropped a device that hit a house in Sarmin on 16 March 2015. This was followed by the release of a toxic substance, matching the characteristics of chlorine, that was fatal to all six occupants.
JIM 4th report (21 October 2016):
"Sufficient information" to conclude that on 16 March 2015 a Syrian armed forces helicopter dropped a device from high altitude which hit the ground in Qmenas and released the toxic substance that affected the population.
Marea, Aleppo province
21 August 2015
FFM report S/1320/2015 (29 October 2015):
"Utmost confidence that at least two people were exposed to sulfur mustard."
JIM 3rd report (24 August 2016):
"Sufficient information to conclude that Islamic State in Iraq and the Levant (ISIL) was the only entity with the ability, capability, motive and means to use sulfur mustard in Marea on 21 August 2015."
Marea, Aleppo province
1 September 2015
FFM report S/2017/2022 (24 January 2022):
"Reasonable grounds to believe that a vesicant chemical substance from 1.A.04 scheduled chemicals to the Convention was used as a weapon."
Marea, Aleppo province
3 September 2015
FFM report S/2017/2022 (24 January 2022):
Unable to establish whether or not chemicals were used as a weapon.
2016
Saraqib, Idlib province
1 August 2016
FFM report S/1901/2020 (1 October 2020):
Unable to establish whether or not chemicals were used as a weapon.
Aleppo
2 August 2016
FFM report S/1444/2016 (21 December 2016):
"Cannot confidently determine whether or not a specific chemical was used as a weapon."
Um-Housh (Umm Hawsh), near Aleppo
16 September 2016
FFM report S/1491/2017 (1 May 2017):
Two female casualties "were exposed to sulfur mustard".
JIM 7th report (26 October 2017):
"Confident that ISIL is responsible for the use of sulfur mustard at Umm Hawsh on 15 and 16 September 2016."
Kafr Zeita, Hama province
1 October 2016
FFM report S/2020/2022 (31 January 2022):
"Reasonable grounds" to believe that a chlorine cylinder was used as a weapon.
Al-Hamadaniyah, Aleppo
30 October 2016
FFM report S/1642/2018 (2 July 2018):
"Cannot confidently determine whether or not a specific chemical was used as a weapon."
Karm Al-Tarrab, Aleppo
13 November 2016
FFM report S/1642/2018 (2 July 2018):
"Cannot confidently determine whether or not a specific chemical was used as a weapon."
2017
Ltamenah, Hama province
24 March 2017
FFM report S/1636/2018 (13 June 2018):
"Sarin was very likely used as a chemical weapon in the south of Ltamenah."
IIT report S/1867/2020 (8 April 2020 ):
"Reasonable grounds" to believe that "at approximately 6:00 on 24 March 2017, an Su-22 military airplane belonging to the 50th Brigade of the 22nd Air Division of the Syrian Arab Air Force, departing from Shayrat airbase, dropped an M4000 aerial bomb containing sarin in southern Ltamenah, affecting at least 16 persons.
Ltamenah, Hama province
25 March 2017
FFM report S/1636/2018 (13 June 2018):
"Chlorine was very likely used as a chemical weapon at Ltamenah hospital and the surrounding area."
IIT report S/1867/2020 (8 April 2020 ):
"Reasonable grounds" to believe that "at approximately 15:00 on 25 March 2017, a helicopter of the Syrian Arab Air Force, departing from Hama airbase, dropped a cylinder on the Ltamenah hospital; the cylinder broke into the hospital through its roof, ruptured, and released chlorine, affecting at least 30 persons.
Ltamenah, Hama province
30 March 2017
FFM report S/1548/2017 (2 November 2017):
"Sarin was more than likely used as a chemical weapon."
IIT report S/1867/2020 (8 April 2020 ):
"Reasonable grounds" to believe that "at approximately 6:00 on 30 March 2017, an Su-22 military airplane belonging to the 50th Brigade of the 22nd Air Division of the Syrian Arab Air Force, departing from Shayrat airbase, dropped an M4000 aerial bomb containing sarin in southern Ltamenah, affecting at least 60 persons.
Khan Shaykhun (Khan Sheikhoun), southern Idlib
4 April 2017
FFM report S/1510/2017 (29 June 2017}:
"A large number of people, some of whom died, were exposed to sarin."
JIM 7th report (26 October 2017:
"Confident that the Syrian Arab Republic is responsible for the release of sarin at Khan Shaykhun on 4 April 2017."
2018
Saraqib, Idlib province
4 February 2018
FFM report S/1626/2018 (15 May 2018):
"Chlorine, released from cylinders through mechanical impact, was likely used as a chemical weapon ... The FFM also noted the presence of chemicals that can neither be explained as occurring naturally in the environment nor as being related to chlorine. Furthermore, some of the medical signs and symptoms reported were different to those that would be expected from exposure to pure chlorine. There was insufficient information and evidence to enable the FFM to draw any further conclusions on these chemicals at this stage."
IIT report S/1943/2021 (12 April 2021):
"Reasonable grounds to believe that at approximately 21:22 on 4 February 2018, during ongoing attacks against Saraqib, a military helicopter of the Syrian Arab Air Force under the control of the Tiger Forces hit eastern Saraqib by dropping at least one cylinder. The cylinder ruptured and released a toxic gas, chlorine, which dispersed over a large area affecting 12 named individuals."
Douma, Damascus
7 April 2018
Interim FFM report S/1645/2018 (6 July 2018):
"No organophosphorus nerve agents or their degradation products were detected, either in the environmental samples or in plasma samples from the alleged casualties" (i.e. no sarin).
Team still working "to establish the significance" of "various chlorinated organic chemicals" found in samples from two locations.
Investigation of warehouse and facility suspected by the Syrian authorities of producing chemical weapons in Douma found "no indication of either facility being involved in the production of chemical warfare agents or toxic chemicals for use as weapons."
Final FFM report S/1731/2019 (1 March 2019):
"Reasonable grounds that the use of a toxic chemical as a weapon took place. This toxic chemical contained reactive chlorine. The toxic chemical was likely molecular chlorine."
Aleppo
24 November 2018
FFM report S/1902/2020 (1 October 2020}:
Unable to establish whether or not chemicals were used as a weapon.
Additional FFM documents
S/1191/2014
16 June 2014
Summary report of FFM activities from 3 to 31 May 2014.
S/1318/2015 (29 October 2015); S/1318/2015/Rev.1 (17 December 2015); S/1318/2015/Rev.1/Add.1 (29 February 2016)
Three reports on a series of alleged incidents in 2014 and 2015 notified to OPCW by the Syrian government. FFM said it was unable to reach conclusions because of lack of information.
S/1445/2016
27 December 2016
Summary of FFM activities during 2016.
Corrigendum: S/1191/2014/Corr.1
Corrigendum: S/1212/2014/Corr.1
Corrigendum: S/1645/2018/Corr.1
Corrigendum: S/1626/2018/Corr.1
Additional JIM documents
JIM 1st report (12 February 2016):
Overview of activities.
JIM 2nd report (10 June 2016):
Review of activities.
Syrian response to 3rd report (20 October 2016):
JIM 5th report (13 February 2017):
Review of activities.
JIM 6th report (28 June 2017):
Review of activities.
Remarks by Edmond Mulet (6 July 2017):
Transcript of news conference given by the head of the JIM.
Russian critique of the Khan Shaykhun investigation (10 October 2017)
